This invention provides a pipeline-waste-gas reduction method to reduce the amount of gas wasted by existing high-pressure pipelines having existing pipeline controllers and existing actuator-based control valves.
High-pressure gas pipelines, which can be thought of as “natural gas” pipelines, must be regulated by control valves to allow, prevent, or partially allow flow of high-pressure gas in a given segment of the pipeline. Such regulation is achieved by existing equipment, specifically existing controllers which use a reduced, control-level pressure of the gas in the pipeline as a means of signaling whether a control valve should be closed or partially closed, and existing control valves which employ actuators driven by that same reduced, control-level pressure of the gas in the pipeline. The remote locations of many of the control valves, and the dangers of explosion or failure, influenced the development of the existing system, which uses a portion of the pressure of the gas in the pipeline as a source of motive force, rather than some outside source.
The existing pipeline controllers continuously vent all or some of the control-level gas pressure to the atmosphere for substantially all of the time. This venting is a waste of gas and is a source of pollution, because the gas is mostly methane.
According to a 2015 announcement by the Obama Administration, methane emissions accounted for nearly 10 percent of United States greenhouse gas emissions in 2012, of which nearly 30 percent came from the production, transmission, and distribution of oil and natural gas. The Administration announced a goal to cut methane emissions from the oil and gas sector by 40 to 45 percent from the 2012 levels by the 2025.
The existing gas-venting pipeline controllers and actuator-based control valves are already in place, are reliable, were expensive to procure and install, and would be expensive to replace. Therefore, there is a need for a waste-gas reduction method that can be used with the existing equipment, without negatively affecting the existing equipment's operation or reliability.
U.S. Pat. No. 6,173,735, issued Jan. 6, 2015 to Marney D. Perry, Jr. et al. for “Method and Apparatus for Regulating Gas Flow,” discloses a pilot-operated, pressure-loaded, movable diaphragm-type gas-flow regulator valve, which is used in flow control applications. A regulator body internal port arrangement interconnects two independent throttling mechanisms in series. Two throttle plates are located within the regulator valve body relative to an inlet chamber and an outlet chamber. A movable diaphragm is positioned relative to a throttle plate by a separate pilot control system to vary the area of throttle plate exposed to flow, and, thus, the flow rate of the regulator valve. The throttle plates each have drilled flow apertures, which control flow through the valve. Smaller flow apertures are opened before larger flow apertures as the valve diaphragm lifts, thereby ensuring stability at low-flow conditions, while providing high capacity at maximum diaphragm lift. The configuration of the throttle plates, the inlet chamber, and the outlet chamber substantially reduces operational noise of the gas-flow regulator by minimizing turbulent flow within the regulator valve body.
U.S. Pat. No. 4,921,399, issued May 1, 1990 to Lawrence E. Lew for “Gas Pipeline Temperature Control,” discloses a compressor station for boosting the pressure of gas stream being transported in a pipeline wherein the act of recompressing the gas stream to a desired pressure results in a gas temperature sufficiently high to stimulate cracking activity in the pipeline when the compressed stream gas is re-injected into the pipeline. A method and apparatus are disclosed for cooling a portion of the warm compressed gas to form a cool gas stream and then controlling a division of the cooled stream to supply both a cooled recycle stream for anti-surge control and a cooled stream for mixing with the warm compressed gas for temperature control.
U.S. Pat. No. 5,816,286, issued Oct. 6, 1998 to Gary L. Scott et al. for “Pressure Unloading Pilot Operated Regulator Having Pressure Limiting Check Valve,” discloses a pressure unloading pilot-operated fluid pressure regulator having a throttling element for controlling fluid flow. A pilot amplifier senses regulator outlet pressure and supplies suitable loading pressure coupled from an inlet supply pressure line through a variable flow restrictor to the throttling element. A check valve has a preset differential pressure defined between the check valve inlet and outlet and is mounted in parallel flow with the flow restrictor to limit the maximum differential pressure across the throttling element to the preset differential pressure of the check valve.
U.S. Pat. No. 5,806,553, issued Sep. 15, 1998 to Herbert R. Sidwell for “Fluid Pressure Control and Relief Apparatus,” discloses an apparatus with fluid pressure above a predetermined limit in a fluid pressure system that is reduced by operating a relief valve, having its inlet port connected with the system, in a throttling action. A normally seated valve member is maintained in relief valve closed position by pneumatic pressure on a piston in a chamber of the relief valve. A fluid pressure sensor communicating with the inlet port generates a signal in response to fluid pressure above a predetermined limit received by a sensor signal processor energized by a source of electrical energy, which releases pneumatic pressure in the chamber for a predetermined time interval, allowing system fluid pressure to unseat the valve member and exhaust fluid pressure through the relief valve outlet port.
U.S. Pat. No. 5,391,209, issued Feb. 21, 1995 to Mark J. Pelkey for “Method for Controlling Overpressurization in a Gas Line,” discloses a gas pressure safety device used in the natural gas distribution systems leading to homes or other customers. This safety device is connected to a gas-venting device that allows excess gas to exit therefrom. The safety device is made up of a needle valve, a pressure-sensing pilot and a spring-diaphragm actuator. The needle valve is used to restrict the rate of gas flow into the actuator to a rate less than that that can be vented by the pressure-sensing pilot. When an excess pressure is generated in the distribution system, the pressure-sensing pilot senses when to exhaust the excess gas through the actuator and out of the gas-venting device to the atmosphere.
Russian Patent No. SU 767,721, issued Sep. 30, 1980 to Berezhnoj Nikolaj et al. for “Pressure Regulator,” discloses an automatic adjusting device and can be used to control pressure or volume in the pipelines for oil and gas industries. The purpose of the invention is to increase reliability of the regulator. This object is achieved by introducing a liquid-filled chamber with a sensor and functional contacts, and gas-filled sealed bellows mounted freely in the chamber. Providing smooth pressure regulation helps to, for example, reduce specific consumption of the active agent in a gas-lift well operation, and the delay in signal transmission increases reliability of the actuating mechanism operation. The pressure regulator includes a chamber completely filled with clean stable liquid, a suspended gas-filled sealed bellows, an adjustable sinker, sensitive element, valves, a pressure gauge, upper functional contacts, lower functional contacts, pipeline, electrical transmission, and actuator. The device operates as follows. In the rest position, the bellows is in an expanded state, and the sensitive element is compressed. The volumetric weight of the bellows with the weight is less than the weight of liquid. Therefore, the bellows floats to the contacts and closes the circuit. At the same time, the electrical member keeps the contacts closed. Any excessive pressure is transmitted through the sensor. At that time the volume of the bellows is decreased according to the Clapeyron-Mendeleev equation. The volumetric weight of the bellow increases and becomes greater than the weight of the liquid, which results in lowering of the bellows into the liquid. The contacts open, while the contacts close. As the result, the transmitter opens the throttle in the actuator. When the pipeline pressure decreases, the process is reversed. The bellows decreases its volumetric weight. When the volumetric weight of the bellows is less than the weight of the liquid the bellows floats. The contacts become open, while the contacts close. The transmitter begins to close the throttle of the actuator.
Chinese Patent No. CN202040548, issued Nov. 11, 2011 to Huang Songli for “Natural Gas Relief Device with Venturi Relief Pipe,” discloses a natural gas relief device with a venturi relief pipe comprises a natural gas inlet pipe, a heat exchanger, a venturi relief pipe, a pressure regulator, a filter, a flow meter and a natural gas storage cabinet, wherein the natural gas inlet pipe, the heat exchanger, the venturi relief pipe, the pressure regulator, the filter, the flow meter and the natural gas storage cabinet are connected in series through natural gas pipelines, the heat exchanger is a coil type indirect heat exchanger, an electromagnetic valve is arranged on a heat exchanger outlet pipe, a pressure gauge is arranged on the natural gas pipe at an outlet of the venturi relief pipe, a pressure regulator inlet valve and a pressure regulator outlet valve are arranged on the natural gas pipes at an inlet and an outlet of the pressure regulator respectively, and a gas cabinet inlet valve is arranged on the natural gas pipe in the front of the natural gas storage cabinet. The natural gas relief device has the advantages that 22 MPa inlet pressure and below of compressed natural gas is reduced to 1.2-1.8 MPa by means of the venturi relief pipe, then the gas enters the pressure regulator be subjected to pressure reduction to 0.1-0.4 MPa, and accordingly a pressure regulation system and a heat exchange system are omitted. The natural gas relief device is simple in structure, safe, reliable, convenient to operate, and low in equipment manufacturing cost and operational cost.
Chinese Patent No. CN203630649, issued Jun. 4, 2014, to Chen Yanshan et al. for “Gas Flow or Pressure Adjustment Device,” discloses a gas flow or pressure adjustment device. The device comprises a main pipeline and a gas backflow pipeline. An inlet valve, a gas compressor, and an outlet valve are sequentially arranged in the main pipeline. The gas backflow pipeline is provided with an adjusting valve, and connected with the gas compressor in parallel on the main pipeline. According to the gas flow or pressure adjustment device provided by the utility model, the gas backflow pipeline is used for adjusting the air pressure of the main pipeline to keep the air pressure of the main pipeline to be uniform and stable, thereby preventing local overlarge air pressure of the pipeline, and ensuring the transmission safety of the pipeline; besides, the adjusting valve is adopted in the gas backflow pipeline to control the flow of gas, and compared with control valves with precise control components, such as gas flow controllers, gas flow adjusting valves, etc., the adjusting valve has higher adaptability for the gas flowing there through, being suitable for gas transmission applications in a wider range.